Artificial ventilation with PEEP; the influence on cardiac output in the simulated normo-, hypo- and hypervolemic state.

Observations of the influence of artificial ventilation with PEEP on cardiac output are unequivocal. Not only the measure of the end-expiratory pressure and lung compliance play a role, but also the circulating blood volume. In healthy laboratory animals a state of normo-, hypo- and hypervolemia was simulated by changes in position in neurolept-anesthesia. In all cases artificial ventilation with PEEP induced a decrease of cardiac output as a consequence of a decrease of stroke volume. These results are discussed. The conclusion is drawn that a change in stroke volume during artificial ventilation with PEEP is not only dependent on the level of end-expiratory pressure and pulmonary compliance but also on that portion of the Starling curve where the heart at that instant is functioning.